1. Field of the Invention
The present invention relates to a computer system, and more particularly, to a computer system capable of playing video when the computer is powered off.
2. Description of the Prior Art
Since electronics technology has progressed, electronic devices, such as personal computers, notebook computers, and personal data assistants, have become available to everyone. In addition to data management, such devices also allow access to the Internet and can serve audio and video entertainment, adding more fun to a busy life.
For audio and video entertainment, CD-ROM, DVD-ROM, or CD-RW implemented in a computer system are commonly used for playing video multimedia, such as VCDs and DVDs. After the operating system of the computer is loaded, a user can enjoy the video and audio via the display and the speaker of the computer. However, the power supply of the computer system only provides power to the optical disk drive after the computer system is booted, and only then the optical disk drive is capable of being operated. If the computer system is powered off, the optical disk drive does not work. Therefore, the computer system must be powered on before playing video multimedia. The lengthy duration of the booting process for the operating system renders playing video multimedia undesirable.
Regarding an optical disk drive capable of being operated when the computer is powered off, there are related teachings in U.S. Pat. No. 6,279,056, No. 6,266,714, and No. 6,006,285. These patents disclose computer systems capable of playing audio CDs in a CD-ROM drive independent of the operating system by switching into an audio CD mode. The computer systems disclosed in these patents are capable of playing audio CDs by using an interrupt signal for system management or by using the playing function of the CD-ROM drive when the operating system, the CD-ROM drive software, and application programs are not completely loaded.
FIG. 1 shows a computer system 1 capable of playing video multimedia when the computer is powered off, disclosed in U.S. patent application Ser. No. 11/096,332. The computer system 1 can play data in a multimedia source 3 of a storage medium via a display 2, and can be a personal computer, a notebook computer, or other electronic device having an access device 12 capable of accessing the multimedia source 3. In addition to the access device 12 mentioned above, the computer system 1 further comprises a power supply 11, a switch circuit 13, a host 14, a multimedia processing unit 15, and a display control unit 16.
The power supply 11 provides power to the access device 12, the switch circuit 13, the host 14, and the multimedia processing unit 15. The access device 12 can access the multimedia source 3 of the storage medium and generate a data signal 101 to the switch circuit 13. The switch circuit 13 is used for switching to a computer mode or a multimedia mode in the computer system 1. The host 14 executes common computer functions, and outputs a host signal 102 to the display control unit 16. The display 2, electrically connected to the display control unit 16, is used for displaying images of the computer.
When switching to the computer mode, the access device 12 can be electrically connected to the host 14 via the switch circuit 13, so that the host 14 can receive the data signal 101 from the switch circuit 13 and output the host signal 102 to the display control unit 16. Then, the display control unit 16 outputs the host signal 102 to the display 2 for showing images related to the operating system or other programs (i.e. windows or screens).
When switching to the multimedia mode, the access device 12 can be electrically connected to the multimedia processing unit 15 via the switch circuit 13, so that the multimedia processing unit 15 can process the data signal 101 from the switch circuit 13 to generate a multimedia signal 103 inputted into the display control unit 16. Then the display control unit 16 scales the multimedia signal 103 according to the size of the display 2 for displaying the multimedia signal 103. Therefore, although the host 14 is not powered on, the data of the multimedia source 3 of the storage media can be read by the access device 12, and processed and displayed by the multimedia processing unit 15.
Whether the display control unit 16 receives the host signal 102 output from the host 14 in the computer mode or receives the multimedia signal 103 output from the multimedia processing unit 15 in the multimedia mode, the display control unit 16 must distinguish video signals for the computer mode or the multimedia mode so as to scale video signals for the display 2. Therefore, the design of this prior art system becomes more complex.